There has been proposed, in a data processing system such as a workstation and a personal computer, an electronic filing system (PUPA 6-168276) or an image database system (PUPA 4-28786) for recording, saving and re-utilizing document image data. Also, an interactive processing system (PUPA 6-259211) has been disclosed in which a plurality of interface parts (menu and the like) for executing user interface function on the display screen of a display device are disposed in a manipulation screen panel of one window.
Further, among contributions to expansion of man-machine interface function of such information systems, a window display method has been provided (“DocuPlus V1.0 Operation Guide”, -1-j, pp. 1–5, Jan. 29, 1997, IBM Japan) in which; in displaying image data having a page delimiter on a display screen, images of all pages are displayed in a reduced form in the window together with a main screen which displays a part of pages with enlargement, and mouse clicking on a reduced screen of a page (called thumb nail) to be moved causes the main screen to be replaced with that page. With this window display method, the user can visually confirm the page to be moved, easily select the page of the desired screen simply by mouse manipulation and immediately confirm the detail of the content in the enlarged screen so that searching information is expedited with ease.
In the above described window display method, however, it is necessary to adjust the display position of the main screen after the page has been switched because the area displayed in the main screen is not shown in the reduced screen in switching the screen which is to be displayed with enlargement. In addition, when the reduced screen to be displayed with enlargement lies at the edge of the screen, adjustment of display position of the main screen has to be done at the edge of the window screen. Further, when a preceding or a next page which does not appear on the display screen is to be manipulated, the user has to command scrolling each time it is manipulated.